This work constitutes the second volume of the trilogy entitled - "THE LARGER WORLD." As such, the bulk of the information is a more in depth look at the subject matter found within the first book - "Beyond the Astral Planes." The compelling issues delineated within its pages are further expounded upon by showing the scientific and philosophical aspects of both. In addition, it explains the thirteen forces of the universe, what colors they represent, their mathematical sequences, and which musical notes they sound. Also covered are the theological overtones that are so important within the previously mentioned attributes.
"I read this book after having read Mr. Parkes’ 1st book in the series, Beyond the Astral Plane. I found that it was a more in depth look at the phenomenon known as OBE. I found the book to be informative and easy to comprehend. This book delves into the possibilities and reasons for pursuing an out of body experience. I like the fact that it focuses on cause and effect, rather than any form of mysticism. I recommend Threshold of Perception for the novice as well as anyone who has had some success with OBE’s."